U.S. Pat. No. 4,913,461 discloses an apparatus which includes an inflatable air bag for restraining a vehicle occupant. The apparatus also includes an inflator for inflating the air bag. The inflator has a cylindrical housing which contains a gas generating material. The gas generating material in the housing rapidly produces a large volume of gas for inflating the air bag when the inflator is actuated. The housing also has a plurality of gas outlet openings for directing the gas to flow outward from the housing to the air bag.
The apparatus disclosed in the '461 patent further includes a mounting plate for mounting the inflator and the air bag on a vehicle steering column. The mounting plate has a flat peripheral wall which is connectable directly to the vehicle steering column. The mounting plate also has a cylindrical wall which projects from the flat peripheral wall. The cylindrical wall of the mounting plate defines a compartment in which the inflator housing is received. After the housing is moved into the compartment in the mounting plate, a retainer ring is moved into the compartment over the housing. The retainer ring is thus moved into a position in which it is located radially between the housing and the cylindrical wall of the mounting plate. The cylindrical wall of the mounting plate is then deformed radially inward against the retainer ring to lock the retainer ring within the compartment in the mounting plate. The retainer ring then blocks the housing from moving out of the compartment, and also holds the air bag against the mounting plate. The inflator housing and the air bag are thus connected to the mounting plate by the retainer ring.